The Animal Pathobiology Core is designed to provide animal breeding, maintenance; and phenotyping resources for program research projects with a focus on aging and mitochondrial integrity. The Core addresses the animal needs of the program project in a way as to increase the efficiency of animal use. Two common themes are prevalent: 1) the use of genetically altered mice and 2) the use of whole animal assays to help characterize features of longevity and aging. The Specific Aims are to: 1) Maintain breeding colonies for new and established lines of mice. It is essential for aging studies that the integrity of the genetic alteration of a specific line be maintained over several generations of backcrossing using sound breeding practices and accurate record keeping. In addition, basic observational assessments will be performed at the colony level to detect any unusual characteristics of newly generated mouse lines. 2) Conduct caloric restriction and aging studies in mice. The increased health vigor and longevity of calorically restricted mice will be compared to the ability of mitochondrial anti-oxidant and DNA polymerase genes to induce similar improvements in genetically manipulated mice. 3) Identify pathobinlogical features in aging cohorts of newly generated mouse lines using specialized phenotyping procedures; these are necessary to detect phenotypic differences not easily discemable by gross observations. They will include clinical and histopathological assessments of multiple organ systems as well as assessments for bone density, cataracts, memory, and motor function Consolidation of animal resources focused on maximizing efficiency and minimizing costs is essential to the success of this program project.